I've been racing sprint karts for more than 10 years now and my unlce is one of the best Kart tuners / engine builders in Australia.
for more info try;
www.kartforce.com.au
As with race cars, starting karting, there are a lot of things you need to consider before jumping straight in with both feet.
Budget being the biggest factor / restriction facing anyone in motorsport.
You will also need to look at what you want from the sport and this will affect which club you join, what type of gear you purchase, how often you race, which kart shop / engine builder you go with etc,etc,etc.
Pm me if you would like some more info.